Since you mentioned that before me, I'm going to link: https://en.wikipedia.org/wiki/Worlds_in_Collision https://en.wikipedia.org/wiki/Worlds_in_Collision It

Since you mentioned that before me, I'm going to link: https://en.wikipedia.org/wiki/Worlds_in_Collision https://en.wikipedia.org/wiki/Worlds_in_Collision It may not be very good as science fiction, but it's an interesting historical/social phenomenon.